Dryer with ejectors



F. T. TAYLOR DRYER WITH EJECTORS Dec. 22,1970

3 Sheets-Sheet 1 Filed May 6. 1968 Frederick T. Ta gl or BY INVENTOF?dag /W F. T. TAYLOR DRYER WITH EJECTORS Dec. 22, 1970 3 Sheets-Sheet 3Filed MayG 1968 Frederi ckT. To 3101 BY INVENTOR fli fgs.

Dec. 22,, 1970 TAYLOR 3543,13

' DRYER WITH EJECTORS Filed May 6. 1968 3 Sheets-Sheet T6 Frederick T.Tcryl or INVENTOR United States Patent 3,548,513 DRYER WITH EJECTORSFrederick T. Taylor, 3274 NE. Everett St., Portland, Oreg. 97232 FiledMay 6, 1968, Ser. No. 726,980 Int. Cl. F26!) 19/00 US. Cl. 34-205 7Claims ABSTRACT OF THE DISCLOSURE A dryer is disclosed herein includingan elongated drying chamber through which articles to be dried travel,an elongated plenum chamber extending alongside the drying chamber, ablower section for producing a current of gas along and through theplenum chamber, and conduit means for conveying gas from the plenumchamber to the drying chamber, including plural ducts distributed alongopposite sides of the dryer and ejectors communicating with the ductsfor ejecting gas into the drying chamber with such ejected gas impingingon articles traveling through the chamber.

This invention relates to drying apparatus, and more particularly, tosuch apparatus which is employed to dry articles such as sheets of woodveneer.

Among the more common forms of conventional veneer dryers are so-calledforced circulation-type and jet-type dryers. Each of these typesnormally includes multiple sections set end-to-encl forming an elongateddrying chamber for the dryer, and power-driven conveyer means extendingalong and through the drying chamber for conveying sheets of veneerthrough the chamber.

A forced circulation-type dryer normally includes a single blowersection for producing a current of air, and a single heating section forheating the air. In such a dryer, air flow typically takes placegenerally longitudinally of the dryer, with air flowing from the blowersection in a path extending alongside the drying chamber from the infeedtoward the discharge end of the dryer, then into the drying chamberadjacent the discharge end of the dryer, and then back along the dryerthrough the drying chamber countercurrent to the flow of veneer.

The usual jet-type dryer, in contrast, includes a blower and heater foreach dryer section, with means provided for directing air at localizedpoints in jets impinging on opposite faces of veneer traveling through asection. Substantially no longitudinal flow of air takes place fromsection to section through such a dryer.

A forced circulation dryer of the type described has the advantage ofrequiring only a single blower and heater section for the whole dryer,and thus is relatively inexpensive to construct, operate and maintain.However, drying action in such a dryer depends almost entirely on airwiping along the faces of veneer sheets, and is relatively slow. A jetdryer, on the other hand, may be operated to dry veneer much morequickly, since it produces direct impingement of air jets on veneerfaces. However, such a dryer is substantially more expensive toconstruct and maintain than a forced circulation dryer, because of thefact that a jet dryer requires a blower and heater for each of its dryersections. A further disadvantage with known jet dryers is that the airimpingement action which they produce sometimes tends to causecasehardening of veneer, which impairs proper drying.

Thus, a general object of the present invention is to provide animproved form of dryer for drying articles, which has many of theadvantages of known dryers as described without the attendantdisadvantages.

More particularly, an object of the invention is to provide a noveldryer having an elongated drying chamber Patented Dec. 22, 1970 throughwhich articles to be dried travel, wherein an impingement drying actionfor such articles is produced at points spaced along the length of thechamber without the need for multiple blower sections in the dryer.

A related object is to provide such a dryer which includes a blowersection producing a current of gas, a heating section for heating gas,and novel conduit means for receiving heated gas and directing such gasinto the drying chamber in plural streams spaced along the length of thechamber with such streams impinging on articles traveling through thechamber.

Another object is to provide such a dryer wherein the conduit meansenables a major portion of the gas returning through the drying chamberto be recirculated to the chamber. With such recirculation possible,waste of heated gas is held to a minimum, and circulation of gas in thedryer is readily performed by a single blower sec tion.

According to the invention, the dryer includes a conveyer deck extendingalong and through the drying chamher for conveying articles from one endto the other of the dryer, and the conduit means includes novel airejectors that extend across, and are distributed along the length of thedrying chamber on opposite sides of the deck. The conduit means furtherincludes novel ducts through which gas coming from the blower section issupplied to the ejectors. The ejectors have elongated slots positionedclosely adjacent the deck, and through these slots gas which is suppliedthe ejectors is directed onto opposite faces of articles traveling onthe deck. The ejectors are constructed and mounted in a manner enablinggas, once ejected, easily to return along and through the drying chamberback to the intake of the blower section.

The invention also features a novel flow control for each of the ductsfor controlling the flow of gas through the ducts to the ejectors.

Yet another object of the invention is to provide a dryer of the type sofar described which further includes deflectors spaced along the lengthof the drying chamber located toward the infeed end of the dryer fromthe ejectors, adapted to deflect gas returning through the chamberagainst articles traveling on the conveyer deck.

Various other objects and advantages which are attained by the inventionwill become more fully apparent as the description which follows is readin conjunction with the accompanying drawings, wherein:

FIG. 1 is a somewhat simplified perspective view illustrating a veneerdryer constructed according to the invention;

FIG. 2 is an enlarged, fragmentary, perspective view illustrating asection of the dryer of FIG. 1 which employs gas ejectors ascontemplated herein;

FIG. 3 is a fragmentary perspective view, on a larger scale than FIG. 2,illustrating portions of ejectors employed in the dryer section of FIG.2, with such ejectors removed from the dryer;

FIG. 4 illustrates, on approximately the same scale as FIG. 3, a portionof a flow control means employed in the dryer section of FIG. 2;

FIG. 5 is a simplified, longitudinal, cross-sectional view, on a largerscale than FIG. 3, illustrating how gas is ejected onto faces of veneersheets traveling adjacent the ejectors of FIG. 3;

FIG. 6 is a simplified longitudinal view, partly in cross section, onapproximately the same scale as FIG. 3, illustrating a section of thedryer of FIG. 1 which employs deflector assemblies as contemplatedherein;

FIG. 7 is a fragmentary perspective view, on a larger scale than FIG. 6,illustrating one form of air deflector assembly with the same removedfrom the dryer; and

FIG. 8 is a fragmentary perspective view, on the same scale as FIG. 7,illustrating another form of deflector assembly removed from the dryer.

It should be understood that while the present invention has particularutility in the drying of wood veneer, and is described in connectionwith such veneer for the purpose of illustration, the invention is notlimited to such application, but may be used as well in the drying ofother kinds of articles. Further, air is ordinarily the gas employed insuch drying, but the use of this specific gas is not required.

Turning now to the drawings, and referring first to FIG. 1, illustratedgenerally at is a veneer dryer constructed according to the invention.The dryer includes an infeed end 10a at which it receives sheets ofveneer to be dried, and a discharge end 10b from which dried sheets aredischarged. Adjacent the base of the dryer, and indicated generally at11, is housing structure defining an elongated drying chamber for thedryer. The drying chamber extends along and through multiple dryersections, designated by even numbers 12 through 34, which follow oneanother along the dryer. Positioned adjacent dryer section 34 is what iscalled a dead air section 36, and adjacent section 36 is a coolingsection 38.

Extending along and through sections 12 through 38 of the dryer aremultiple conveyor decks for transporting sheets of veneer through thedryer from end 10a to end 10b. The dryer illustrated includes four ofsuch decks indicated generally at 40, 42, 44, 46. Each deck comprisesmultiple pairs of vertically spaced rolls, such as rolls 42a, 42b, fordeck 42, that extend across the dryer and that are distributed along thelength thereof. The rolls forming each deck are driven by a suitablepower drive means 48 which is appropriately connected to the rolls bymeans of chains, such as chain 50, connected to the rolls of deck 42.

Extending over the tops of dryer sections 14 through 34 (but not oversection 12) is an elongated, substantially horizontal roof illustratedin dashed outline including an expanse 52a which covers sections 14through 22 and which extends substantially completely across the widthof the dryer, and an expanse 52b which extends over sections 24 through34 and which is somewhat narrower than expanse 52a. As can be seenclearly in FIG. 1, the opposite side edges of expanse 52b are locatedlaterally inwardly from the opposite sides of dryer sections 24 through34.

Dryer 10 further includes along its opposite sides above sections 12through 34 side walls, such as wall 54, end walls, such as wall 56,extending transversely between and joining with the side walls, and topstructure 58 spanning and joined to the side and end walls. The side andend walls, top structure, and previously-described roof togethercomprise casing structure herein defining an elongated plenum chamberextending along the length of the dryer over dryer sections 12 through34.

Suitably mounted inside the plenum chamber adjacent end 10a of the dryerare a pair of laterally spaced fans, or blowers, indicated generally indashed outline at 60, 62. The blowers together comprise a blower sectionfor the dryer. Blowers 60, 62 are driven by electric motors 64, 66,respectively, mounted on top structures 58, and such motors areconnected to the blowers by means of belts 68, 70 which extend throughsuitable belt wells, such as well 72 for belt 68, provided adjacent thetop structure. An appropriate vent 74 is provided for venting the beltwells.

Also mounted inside the plenum chamber, and located toward the dischargeend of the dryer from fans 60, 62, is a heating section 76 (shown indashed outline) for heating air in the dryer. The heating sectionincludes conventional burner units (not shown) which on operation heatair flowing through the section. A feed manifold 78 is provided forfeeding fuel to the burner units of the heating section. A mixing pipe80 connects both to manifold 78 and to a blower 82 which is driven by amotor 84. Pipe 80 is further connected to a suitable source of fuel,such as a fuel gas, by means of a conduit 86, and the intake of blower82 is connected to a conduit 88 through which the blower receives air.With blower 82 driven by motor 84, air is drawn in through conduit 88and forced into pipe where it is mixed with fuel gas supplied throughconduit 86. The mixture is then supplied through manifold 78 to theburner units where it is burned to heat air in the dryer.

Located in-between the blower and heating sections is a main vent 90 forthe dryer which connects with the interior of the plenum chamber. Thisprovides for the venting of part of the air returned on circulation ofair within the dryer.

Previously-mentioned dead air section 36, where it joins with sections34, 38 of the dryer, is provided with the usual baflles (not shown)which inhibit any substantial air flow through the section. The dead airsection functions as an insulator between sections 34, 38. A vent forthe section is shown at 92.

Suitably mounted on top of cooling section 38 is a blower 94 which isdriven by a motor 96. Section 38 is provided with a vent 98. Fan 94functions to circulate cool air over sheets of veneer immediately priorto when they emerge from end 10b.

Illustrated in simplified dashed outline inside the dryer, adjacentlaterally opposite sides of section 24 through 34, are a series ofvertically-disposed ducts a, 1001:. The upper ends of the ductscommunicate with the interior of the plenum chamber adjacent theopposite side margins of roof expanse 52b. In general terms, these ductsform part of conduit means according to the invention interposed betweenthe plenum and drying chambers for conveying air from the former to thelatter.

Considering briefly the general nature of air heating and fiow thattakes place inside the dryer with blowers 60, 62 and the heating sectionoperating, the blowers produce a current of air which flows along andthrough the plenum chamber in a direction toward end 10b of the dryer.As the air passes through heating section 76 it is heated to the desiredtemperature. From the plenum chamber air flows downwardly in paths alongopposite sides of the dryer defined by the ducts adjacent dryer section24 through 34, and from there, is ejected as will be later described inmore detail, into the drying chamber.

In the drying chamber, the air circulates adjacent opposite sides ofveneer sheets traveling through the chamber producing drying of suchsheets, The air returns by flowing longitudinally through and along thedrying chamber toward end 10a of the dryer. The air then flows upwardlyout of section 12 back into the plenum chamber, such upward flow beingpossible by reason of the fact that roof expanse 52a does not extendover section 12. Upon retuming to the plenum chamber, the air is drawnthrough blowers 60, 62, and a major portion of it is recirculatedthrough the heating section down along the plenum chamber and back intothe drying chamber. The small portion which is not recirculated isvented to the atmosphere through vent 90. Fresh air is constantly drawninto the dryer through conduit 88 to replace air which is vented.

Turning now to FIG. 2 which illustrates portions of dryer section 26 inmore detail, and describing the construction of the frame for thesection, extending transversely of the dryer are rectangular frameassemblies such as the one illustrated comprising upper and lower transverse members 102, 104, and upright members, 106, 108 at opposite sidesof the dryer, extending between and joining the transverse members.Extending longitudinally of the dryer and joining adjacent frameassemblies on each side of the dryer are spaced upper members 110, 112and spaced lower members 114, 116. Mounted on and extending verticallybetween these longitudinally extending members, and spaced along thelength of the dryer section, are posts, such as inner posts 118 betweenmembers 110, 114 and outer posts 119 between members 112, 116.

Ducts 100a, 100b were earlier described as functioning to convey airbetween the plenum and drying chambers. A duct may be constructed asbest illustrated for the duct 100a shown in FIG. 2, and may comprise aside panel 120 closing off the outer side of the duct, a floor plate 121closing off the ducts base, and partitions such as the one shownpartially at 122 bounding the duct adjacent forward and rear ends of adryer section,

A flow control is provided for controlling air flow through a duct.Exemplifying such a control is the one shown at 126 for duct 100a inFIGS. 2 and 4. Considering the construction of control 126, it comprisesan elongated, substantially rectangular frame including side bars 130,132, and end bars, such as end bar 134, joining the side bars adjacentopposite sets of ends thereof. The frame is mounted adjacent the top ofthe duct, with side bars 130, 132 mounted on longitudinal members 110,112, respectively, and the end bars mounted on the transverse members,such as member 102, adjacent the ends of section 26.

Extending transversely between and pivotally mounted on side bars 130,132, at points spaced along the lengths of the bars, are elongatedrectangular vanes 136. The vanes are connected together for simultaneousoperation by an overhead bar 140 which is connected to the vanes throughdepending elements 142 which elements include journals 142a receivedwithin cylindrical collars 146 on the vanes. A shaft 150 (FIG. 2)connected to one of the vanes in a flow control extends laterally to theoutside of the dryer. With turning of the shaft the inclination of thevanes may be adjusted to change the flow of air into a duct.

Within a dryer section, rolls such as rolls 42a, 42b making up a dryerdeck extend between and are jo'urnaled on opposing inner posts for thesection. In FIG. 2, only portions of such rolls are shown.

Suitably mounted on the inner posts of the dryer section frame, andextending transvesely of the dryer, are vertically extending stacks ofair ejectors, such as the stack shown in FIG. 2 including ejectors 152,154, 156, 158 and 160. These ejectors are mounted with ejector 154located between decks 40, 42, ejector 156 between decks 42, 44, andejector 158 between decks 44, 46. Ejector 152 is located below deck 40,and ejector 160 is located above deck 46. The ejectors are spaced apartto accommodate the travel of veneer along the various decks between theejectors. In each of the dryer sections 24, 26, 28, 30, 32, and 34,multiple stacks of ejectors follow one another in the section, allcommunicating with the ducts supplying the dryer section.

Referring now to FIG. 3 which illustrates portions of decks 40, 42 andejectors 152, 154, 156 removed from the dryer, and considering first theconstruction of ejector 154 (which ejectors 156 and 158 resemble), itcomprises an elongated hollow unit having opposite ends, as illustratedby end 154a, which are open. The unit includes a pair of elongated,vertically spaced, hollow sections 154b, 1540 which define separatepaths for the flow of air along and through the unit. The sectionscommunicate with one another adjacent the opposite ends of the unit, ascan be seen with reference to end 1154a, The sections, progressinginwardly from opposite ends of the unit, diminish in crosssectionalarea, and thus, an elongated, somewhat diamondshaped opening or passage154d exists between the channel sections. Suitable braces such as braces162, 164, are provided between the sections.

The unit has upper and lower, horizontally disposed faces 154e, 1541,respectively, facing dryer decks 42, 40, respectively. Formed in faces1546, 154 are elongated slots, or orifices, 154g, 1541:. Thesecommunicate with the interiors of sections 154b, 1540, respectively.

Considering now the construction of ejector 152, this ejector resemblesin construction a single section of ejectors 154, 156, 158. Thus, itcomprises an elongated section 152a which is open adjacent its oppositeends and which, progressing inwardly from such ends, diminishes incross-sectional area. The ejector includes an elongated,

horizontally disposed face 1521; facing dryer deck 40, and an elongatedslot 152a formed in this face. Air ejector 160 is substantially the samein construction as ejector 152, but i positioned with its slotted facefacing downwardly toward dryer deck 46. The ejectors of other stacks inthe dryer resemble the ejectors in the stack just specificallydescribed.

Explaining how the air ejectors in the stack function to introduce airinto the drying chamber, and referring to FIGS. 2, 3, and 5, it will berecalled that air flows from the plenum chamber downwardly along thesides of the dryer in ducts 100a, 1001:. Ducts 100a, 10Gb communicatewith opposite ends of the various ejectors, and hence, introduce airinto the ejectors from opposite sides of the dryer. Air within thehollow sections of the ejectors flows out through the slots, and isdirected against opposite faces of veneer sheets traveling on theconveyor decks.

Referring particularly to FIG. 5 where veneer sheets 165, 167 are shownon decks 40, 42, respectively, and portions of previously-describedejectors 152, 154, 156 are illustrated, arrows indicate how air flowtakes place adjacent the ejectors. Air flowing out of the ejectors slotsimpinges on opposite faces of the sheets, and after such impingement,flows along the sheets countercurrent to the direction in which they aremoving on the decks. In the regions between the confronting faces of theejectors, such flow produces a wiping drying action. The air inreturning to the feed end of the dryer, flows between the decks in thedrying chamber through the passages provided by the spaced-apartsections of the ejectors.

Dryer sections 24, 28, 30, 32 and 34 of the dryer have a constructionsimilar to section 26, and include ducts 100a, 100b, flow controls forthese ducts, and air ejectors disposed in stacks substantially asdescribed for section 26.

Considering now sections 14 through 22 of the dryer, these sections areprovided with appropriate frame structure which is similar inconstruction to the frame structure described for section 26. Posts insuch frame structure journal rolls of the conveyer decks in the dryer asdescribed in connection with dryer section 26. Ejectors, however, may beomitted from sections 14 to 22.

According to the invention, air deflector assemblies are provided insections 14 through 22 whereby air returning through the drying chambertoward infeed end 10a of the dryer is directed against opposite faces ofveneer traveling on the decks. Referring to FIG. 6, which illustratesportions of dryer section 14 (typifying sections 14 to 22), suchdeflector assemblies are disposed in vertically extending stacks, withthe deflector assemblies in a stack illustrated generally at 168, 170,172, 174 and 176. The deflector assemblies are mounted on the innerposts of the dryer section which support the deck rolls, and extendtransversely of the dryer. Assembly 170 is located between decks 40, 42;assembly 172 is between decks 42, 44; and assembly 174 is between decks44, 46. Assembly 168 is located below deck 40, and assembly 176 ispositioned above deck 46.

Considering in more detail the construction of a deflector assemblyprovided between conveyer decks, as exemplified by assembly 174, andreferring to FIG. 7, it comprises, adjacent opposite ends, a pair ofsubstantially rectangular mounting brackets, such as bracket 174a.Suitably joined to and extending between the brackets are elongateddeflector elements 174b, 1740, each of which has a somewhat S-shapedcross-sectional configuration.

Considering the construction of assembly 176, and referring now to FIG.8, this assembly includes, adjacent its opposite ends, a pair ofbrackets, such as bracket 17 6a. Extending between and joining with thebrackets is a single deflector element 176b, which is similar inconstruction to previously-described elements 174b, 174c. Deflectorassembly 168 has a similar construction.

As can be seen in FIG. 6, the deflector assemblies in successive stacksare mounted in such a manner as to accommodate air flow generallylongitudinally through the drying chamber between the various decks,with streams of such air repeatedly being directed against faces of theveneer traveling on the decks thus to produce wiping of the faces withair to promote drying of the faces.

With the dryer described herein, removal of moisture from veneer takesplace quite rapidly, by reason of the impingement action produced in thedrying chamber by the air ejectors provided adjacent the off-bearing endof the dryer, and the wiping action produced by the deflector assembliesprovided adjacent the infeed end of the dryer. Additionally, there is awiping action occurring between ejectors, because of the confrontingfaces of opposed air ejectors which operate to channel air in a narrowpath extending directly adjacent veneer faces.

Drying of veneer is facilitated by virtue of the fact that air flowinginto the ejectors, and hence out of the slots onto the veneer, mayreadily be regulated by the controls which are adjustable to increase ordecrease flow of air permitted through the various ducts provided alongthe sides of the drying chamber. With proper setting of the controls,any tendencies for casehardening to occur may be minimized.

The dryer contemplated operates efliciently, since its constructionenables air to be recirculated with air flowing in paths which extendlongitudinally of the dryer. Waste of heated air is held to a minimum.Moreover, only a single blower and heating section is required toproduce air flow in the dryer, and thus, the dryer may be constructed,operated, and maintained relatively inexpensively.

While a particular dryer has been illustrated herein, it is appreciatedthat variations may readily be made without departing from the spirit ofthe invention. For example, a dryer may be constructed having adiflerent number of dryer sections than the dryer shown. Additionally,the number of such sections having ejectors and deflector assemblies mayvary depending upon the circumstances.

Other variations and modifications will become apparent to those skilledin the art, and it is desired to cover all such variations andmodifications which come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a dryer, housing structure defining an elongated drying chamberwhich articles to be dried travel through,

a conveyer deck extending longitudinally through said chamber forconveying such articles,

casing structure defining an elongated plenum chamber,

said plenum chamber having an inlet and communicating with the dryingchamber adjacent the one end of the drying chamber and having an outletend, conduit means interconnecting the outlet end of said plenum chamberand said drying chamber accommodating the flow of gas from the former tothe latter, said conduit means including plural ejectors spaced atintervals along the length of said drying chamber and located toward theopposite end of said drying chamber from where the inlet end of theplenum chamber communicates with the drying chamber, each ejector havingorifice means through which gas is ejected from the ejector at an angleupon articles carried by said conveyer deck, and

a blower for producing a current of gas along said plenum chamber fromits inlet toward its outlet end and into said drying chamber throughsaid conduit means, said drying chamber constituting a channel extendingto the inlet end of the plenum chamber and channeling gas ejectedthereinto through said ejectors back to the inlet end of said plenumchamber for recirculation.

2. The dryer of claim 1, which further includes a duct 8 for each ofmultiple ejectors connecting the ejector with the plenum chamber, and anadjustable flow control for each duct, adjustable to' control the flowof gas through the duct.

3. The dryer of claim 1 which further includes a second conveyer deckspaced from and substantially paralleling the first-mentioned deck, andwherein said ejectors are located between said decks, each ejectorcomprising an elongated hollow unit extending across the drying chamberwith opposite sides facing the two decks on either side of the unit, andthe orifice means of an ejector unit includes an elongated slotextending longitudinally of the unit in each of the units said oppositesides.

4. The dryer of claim 3, wherein an ejector unit includes a pair ofhollow sections extending along opposite sides of the unit definingseparate paths therein for the flow of gas, and the interior of eachsection communicates with one of the slots in the unit.

5. The dryer of claim 4, wherein the sections of a unit are spacedlaterally of each other to form a passage for the return flow of gasbetween the decks.

6. The dryer of claim 3 which further includes deflectors spaced atintervals along the length of said drying chamber, located between saiddecks and toward said one end of said dryer from said ejectors, adaptedto deflect air flowing through the drying chamber against articlescarried by said conveyer decks.

7. In a dryer, housing structure defining an elongated drying chamberwith which articles to be dried travel through,

a conveyer deck extending longitudinally through said chamber forconveying such articles,

casing structure defining an elongated plenum chamber extending alongthe top of said drying chamber, said plenum chamber having an inlet endcommunicating with the drying chamber adjacent one end of the dryingchamber and an outlet end spaced toward the opposite end of the dryingchamber,

conduit means interposed between said outlet end of the plenum chamberand said drying chamber accommodating the flow of gas from the former tothe latter, said conduit means including plural gas ejectors spaced atintervals along the length of said drying chamber and located toward theopposite end of said drying chamber from where the inlet end of theplenum chamber communicates with the drying chamber, and multiple ductson either side of the drying chamber connecting such ejectors with saidplenum chamber, each ejector having orifice means through which gas isejected from the ejector into the drying chamber, and

a blower for producing a current of gas along and through said plenumchamber and then into said drying chamber through said ducts and saidejectors, said drying chamber channeling gas ejected thereinto throughsaid ejectors back to the inlet end of said plenum chamber forrecirculation.

References Cited UNITED STATES PATENTS 1,138,751 5/1915 Grosvenor34-231X 2,308,767 1/1943 Mayes 34231X 3,371,427 3/1968 Thygeson 34l553,372,630 3/1968 Schmidt 34-156X 3,417,484 12/1968 McCarthy 34160X1,563,963 12/1925 Byrd 342l9 1,668,314 5/1928 Harvey 34224X FOREIGNPATENTS 1,104,437 4/1961 Germany 34-160 MARTIN P. SCHWADRON, PrimaryExaminer H. B. RAMEY, Assistant Examiner

